iPhone In-App Purchase & App Store

I have an iPhone Application written in Xcode. Everything is fully working and completed, except for the part In-App purchase. Since we are selling subscription based service on our app, Apple's guidelines indicate that we must implement In-App purchase and it needs to be done ASAP. We have an API built on our server, the APP will request the API and get all the subscription plans and pricing, once payment is completed it should send information to our API so the buyer gets credited. Now, I have absolutely no idea how the in-app purchases works but I do have an iOS developer account. I need an experienced developer that has worked with inapp purchase api before and implement it to our app. After that, we need you to guide us to submit the application to App store since I have no idea how to do that either. In short: - Add In-App purchase - Help compile and submit app to app store Thanks